﻿#!/usr/bin/env python3

def funca(a:3, b:'hello'=None)->'nothing':
    print(a,b)

def main():
    '''
function annotations -
函数注解本身并没有运行意义,仅供人员方便阅读理解.
    '''
    print(main.__doc__)
    funca(4)
    print(funca.__annotations__)


if __name__=='__main__':
    main()
